Apparatus for applying glue and like adhesives



May 24, 1966 E. w. HARGREAVES 3,252,441

APPARATUS FOR APPLYING GLUE AND LIKE ADHESIVES Filed June 8, 1964 3 Sheets-Sheet 1 Inventor EDWARD WILL/AM F/HAGRE/J v55 Attorneys y 1966 E. W. HARGREAVES 3,252,441

APPARATUS FOR APPLYING GLUE AND LIKE ADHESIVES Filed June 8, 1964 5 Sheets-Sheet 2 22 Inventor Attorney 5 May 24, 1966 E. w. HARGREAVES 3,252,441

APPARATUS FOR APPLYING GLUE AND LIKE ADHESIVES Filed June 8, 1964 3 Sheets-Sheet 5 PHO /0 JCHM/TT I M/VEP 75R IPA/M57570? TAD/6651? pwro JCHM/TT 6/ (STABLE TRANS/670R TP/GGE? 45 POWER JW/TCH Inventor EDWARD W/lL/AM HQKGAEA v A horneyS United A States Patent 3,252,441 APPARATUS FOR APPLYING GLUE AND LIKE ADHESKVES Edward W. Hargreaves, Southampton, England, asslgnor to Cox & Sharland Limited, Southampton, England, a British company Filed June 8, 1964, Ser. No. 373,219 Claims priority, application Great Britain, June 14, 1963, 23,823/63 .4 Claims. (Cl. 118-2) This invention concerns apparatus for applying glue or other adhesives to articles and more particularly although not exclusively to a succession of articles and more particularly although not exclusively to a succession of articles in a manufacturing or assembling process.

It is of course well known in printing, book assembling, box making and carton making to apply glue to selected parts of articles. Generally this is effected by means of a glue bath from which glue is transferred by rollers, at least one of which dips into the bath, to the articles. One of the disadvantages of these known arrangements is that since the glue bath and rollers are continuously exposed to the atmosphere evaporation especially of volatile adhesives takes place, while during temporary stoppages of the plant drying of the glue takes place not only in the bath but on the rollers with consequent need for these to be cleaned.

It is an objectof this invention to provide apparatus for applying glue or like adhesives which avoids or greatly reduces these disadvantages.

According to the invention we provide apparatus for applying glue or like adhesive comprising a glue applying device and a deformable glue reservoir connected together in a substantially air tight manner, means for applying pressure to said reservoir so as, in operation, to force glue from the reservoir into the device and trigger means serving to cause or permit the discharge of glue from said device.

The said glue applying device is preferably in the form of a gun-like member having a small bore nozzle through which glue can be applied to an article and preferably includes a valve member operable in response to said trigger means so as to cause or permit glue to be discharged through the nozzle.

While the said trigger means can be used to control the application of pressure to the glue reservoir and hence to cont-r01 discharge of the glue through the device it is preferred to provide a separate pressure control for feeding glue from the reservoir to the device and a valve controlled by said trigger means.

Preferably the valve member for controlling the flow of glue to the nozzle is arranged to open by movement in the direction of flow of glue since this provides a slight rise in pressure on opening and a slight pressure drop on closing which serves to assist in giving a clean and sharp cutoff of glue flowing through the nozzle.

Various means may be provided for actuating the said valve in response to the trigger means, but it is preferred to provide electromagnetic means for actuating the valve for instance'by providing the valve body with a portion which .is either integral therewith or rigidly connected thereto and which serves as an armature of a solenoid to open the valve when the solenoid is energized. Preferably spring means are provided to close the valve.

The trigger means for actuating the glue applying device are preferably such that the trigger is actuated by the passage of an article to be glued past the trigger means.

Depending on the nature of the articles to which glue is to be applied various types of trigger means may be employed. Thus for instance where cardboard blanks or other relatively heavy and stable articles are to be glued we may provide feelers or like members which on being contacted or moved by a blank to be glued initiate operation of the trigger means. Where however lighter and easily movable articles such as printed paper pages of a book or magazine are to be glued in success-ion these might well be urged out of alignment by any physical contact with a feeler and hence we prefer to provide photoelectric trigger means.

Such photoelectric means preferably include two photoelectric devices one serving to operate said trigger means and cause the glue to be delivered and the other serving to reverse the operation of the trigger means and thus cause or permit the closing of the valve of the device.

The apparatus can comprise a container for glue having a piston or diaphragm one side of which is under the influence of pressure to urge glue in a glue feeding direction or as is preferred We may provide a glue reservoir in the for-m of a bag of synthetic plastic material housed in a-rigid pressure tight container to which compressed fluid e.g. air can be supplied by a valve as required.

One embodiment of the invention will now be described by way of example, with reference to the accompanying drawings in which:

FIGURE 1 is a diagrammatic representation of part of a book section folding machine utilising the invention for applying glue to the sheets which are to be folded into sections.

FIGURE 2 is a sectional side view to an enlarged scale of the glue gun used in the machine illustrated in FIG- URE 1.

FIGURE 3 is sectional view taken on the line III-III of FIGURE 2, and

FIGURE 4 is a diagrammatic representation of the electronic circuitry for con-trolling the glue gun in FIG- URE 1.

Referring to FIGURE 1, two sheets of an eight page section 1 and 2 are shown in transit, in the direction of the arrow, along a conveyor 3 during a folding operation in a folding or book-making machine. The conveyor 3 forms part of the feed table of the machine. A line of glue 4 is shown as already having been applied to the leading sheet 1 while dotted lines indicate where a line of glue 5 will be applied to the second sheet 2. The glue is applied by means of an electromagnetically operable applicator or glue gun 6 which is connected by a tube 7 to a deformable synthetic plastic glue reservoir 8. Reservoir S is disposed in a pressure tight container 9. The space 10 between the reservoir 8 and the container 9 is connected by an air (not shown). A pressure gauge 12 is provided together with a pressure control knob 13. The reservoir is provided with the usual safety valve and a glandless type of cock through which glue is fed at a controlled pressure.

Operation of the glue gun 6 is controlled by means of two photoelectric devices 14 and 15 connected by respective leads 16 and 17 to a control unit 18 which is capable of supplying control current to the glue gun 6 by means of a further lead 19.

Referring to FIGURES 2 and 3 it will be seen that the glue gun 6 comprises an outer casing 20, an inlet coupling 21, for connection of glue feed tube 7 thereto, and a glue outlet nozzle member 22. The bore 23 through the coupling 21 communicates with a space 24 of circular cross-section (see FIGURE 3) and in which an armature ,member 25 of hexagonal cross-section (see FIGURE 3) is movable longitudinally under the influence of current flow through an electromagnetic Winding 26. The armature member 25 is rigidly connected to a valve member 27 which normally seats on a valve seat 28 to form an effective seal to prevent glue passing from the space 24 to the nozle member 22 of the glue gun 6. The use of an armature of hexagonal cross-section movable along a guideway of circular cross-section ensures that accurate pipe 11 to a source of compressed air 3 movement is obtained while glue can still flow past the armature 25. If desired, an armature member of circular cross-section may be providedbut the guideway should then preferably be provided with longitudinal grooves.

The valve chamber or space 29, in which the valve member 27 is located, connects with the small outlet bore 30, of about g" diameter, in the nozzle member 22 by means of three equispaced axially inclined radial apertures, only one aperture 3 1 being visible in FIGURE 2. As can be seen in FIGURE 2, the nozzle member 22 is provided with an oblique nozzle outlet in order that, as shown in FIGURE 1, the glue gun can be mounted at an angle to the vertical with its nozzle tip in light contact with the sheet to be glued.

A return spring 32 is provided between the body member 33 and valve member 27 to urge the valve member 27 toward the valve seat 28 to close the valve. The nozzle member 22 is threadedly mounted on the body portion 33 of the glue gun, shims 34- being provided between the nozzle member 22 and the body portion 33.

The opening movement of the valve member 27 is limited by an integral stop 35 on the nozzle member 22. The magnitude of the movement of the valve member 27 and therefore the size of the valve opening through which glue flows can be altered by altering the total thickness of the shims 34 between the nozzle member 22 and the body portion 33. Diiterent valve openings are, of course, required in dependence on the glue viscosity, the thicker the glue the thicker the shims 34 required.

It will be appreciated that alteration of the magnitude of the movement of valve member 27 also alters its speed of opening and it is desirable to keep the movement of the valve member, and hence the opening and closing times, to a minimum.

The photo-electric devices 14 and in FIGURE 1 each respond to light reflected from a sheet passing beneath them. They both comprise a pair of electric bulbs (one bulb 36 being visible in FIGURE I) mounted on opposite sides of a housing 36' containing a photo transistor. An aperture is'provided in the base of each housing 36' to permit light reflected from a sheet to be incident on the respective photo transistor.

FIGURE 4 illustrates part of the control unit circuitry for utilizing the output of the photo transistors in devices 14 and 15 of FIGURE 1 to control energizing current through the winding 26 (FIGURES 2 and 3) of the glue gun 6. The photo transistor in device 14 is identified as transistor 37 in FIGURE 4, while that in device 15 is identified as transistor 38. Photo transistor 37 is connected through a Schmitt trigger circuit 39 to sharpen any voltage change and an inverter 40 to one input 41 of a two input bi-stable multivibrator 42 and photo transistor 38 is connected through a Schmitt trigger circuit 43 to the other input 44 of the multivibrator 42.

The output of the multivibrator 42 is utilised to control a power transistor used as a switch 45 which is operative, when closed, to connect a source (not shown) of energizing current to the winding 26 of the glue gun 6, or, when open, to disconnect the source of energizing current from the winding 26. Power switch 45 is opened or closed in dependence on the voltage output from the multivibrator 42 which, as will be understood, is determined by the switching state of the multivibrator 42. The multivibrator is switched from a first state to a second state by an output from photo transistor 38 resulting in a signal at input 44 of multivibrator 42 corresponding to the leading edge of a sheet passing the transistor 38 in device 15. It is switched from its second to its first state when an output from photo transistor 37 results in a signal at input 41 corresponding to the trailing edge of a sheet passing the transistor 37 in device 14. When the multivibrator is switched to its first state is is arranged so that this causes the power switch 45 to open and when the multivibrator is switched to its second 4 state it is arranged so that this causes the multivibrator to close switch 45 to supply current to winding 26 of glue gun 6.

Since light reflected from the sheet is utilised to operate the phototransistors, it will be seen from the above that photo transistor 37 and multivibrator 42 must be so connected that a change in light incident on the transistor 37 in a direction from light to dark results in the multivibrator being switched to its first state to open switch 45, while photo transistor 38 and multivibrator 42 must be so connected so that a change in light incident on the transistor 38 in a direction from dark to light results in the multivibrator being switched to its second state to close switch 45, the opposite direction of light change on the respective transistors producing no switching of multivibrator 42.

In operation the sheets are fed along the conveyor 3 (FIGURE 1) and as the leading edge of a sheet passes under the photo-electric device 15 power switch 45 (FIG- URE 4) closes, due to the multivibrator being switched to its second state, to cause energizing current to flow through the winding 26 (FIGURES 2 and 3) of the glue gun 6. The armature 25 thus moves downwardly in FIG- URE 2, along with valve member 27, against the action of spring 32. Glue is then forced out of the space 24 due to the pressure from the glue reservoir and through the valve opening between valve member 27 and seating 28. Glue is therefore forced through the three apertures, such as 31, and out through the nozzle 22 of the gun at a rate governed by the pressure in the glue reservoir. Due to the constant pressure of glue along the feed tube 7 and through the gun 6, a continuous stream of glue is emitted from the nozzle member 22 as the respective sheet, e.g. sheet 2 in FIGURE 1, passes under the glue gun 6. A glue line such as 4 and 5 is thus made on each sheet as it moves beneath the nozzle of the glue gun.

As the trailing edge of the sheet passes under the photoelectric device 14 the light which is incident on the respective photo transistor 37 changes from light to dark and the multivibrator 42 (FIGURE 4) is switched back to its first state to open switch 45 and stop energizing current flowing through winding 26 of glue gun 6. The return spring 32 (FIGURE 2) is then able to move the valve member 27 and armature 25 upwardly in FIGURE 2 so that the valve member again co-operates with valve seat opposite direction to close the valve a slight pressure drop occurs on closing and there is less likelihood of a blob of glue forming on the end of the nozzle of the glue gun and a clean cut to the line of glue is obtained. Furthermore it will be appreciated that only the glue at the end of the nozzle is in contact with the surrounding atmosphere when the gun is not in use, since the glue reservoir 8, tube 7, and gun 6 are connected in an air tight manner. Thus the tendency of glue in the apparatus to evaporate or dry over a period of time is almost entirely avoided. The dry glue at the end of the nozzle can be picked off when the gun is again used or the end can be cleaned wtih a piece of wire. The construction of the apparatus is especially convenient for cleaning.

The apparatus described can be used with volatile or non-volatile glues without the occurrence of some of the drying difficulties experienced with glue rollers and wheels in known glue baths.

As the glue gun 6 is positioned between the photo-electric devices 14 and 15 in the direction of travel of the sheets along the conveyor, the line of glue applied to each sheet commences a short distance after the leading edge of the sheet passes photo-electric head 15 and is terminated a short distance after the trailing edge of the sheet passes photo-electric head 14. This will be clear from FIG- URE 1. The actual start and finish of the glue lines 4 and 5 in FIGURE 1 can be altered by suitable adjustment of the position of the photo-electric heads along a fixed support rod 48. This adjustment can serve for example, to accommodate different sizes of sheets or for altering the length, stroke or position of the glue line applied to the sheet. The glue gun 6 is preferably positioned on rods 46 so that its nozzle is approximately between two rollers of the conveyor.

The quantity of glue applied by the glue gun can conveniently be altered without stopping the machine by means of the pressure control knob 13 on the glue reservoir 9. This is set by the operator to give the required depth of glue dependent on the speed of the sheet and the viscosity of the glue.

In using the machine for the first time it is, of course, necessary to allow glue to flow out of the nozzle for a short time to ensure that all air is pushed out of the glue gun before operational use.

The machine is' applicable to many operations in the printing and allied trades and is capable of operating at relatively high speeds Without spraying. One machine has been operated experimentally at an approximate speed of 10,000 sheets per hour. The operation of the glueing apparatus, is of course, dependent only on the presence of the moving sheets and not on the timing of the rest of the machine.

If desired a temperature-compensating diode may be included in the circuit of each photo transistor to prevent the multivibrator being switched due to changes in temperature caused by electric bulbs, sunlight, electric motors or other external sources of heat.

In the embodiment described above only one electromagnetic winding 26 is provided for operating the glue gun 6. It will be appreciated that more than one winding may be provided and that, if desired, a reversal of current in the winding 26 (FIGURE 2) may be utilised to move the armature 25 in a direction to close the valve to cut otf the flow of glue, as well as or instead of the return spring 32.

A plurality of glue guns 6 may be provided, if, desired, either all operated by the same pair of photo-electric devices or all operated independently.

Although the invention has been described with reference to a machine utilizing photo-electric devices to operate the glue gun, it will be appreciated that it is not limited thereto. For example, especially w-tih heavier material such as cardboard which is to have glue applied to it, mechanical finger tip contacts and possibly relays may be used to control the operation of the glue gun. Instead ot tion, nozzles of varying shapes may be fitted to provide a variety of glue line widths. To facilitate the changing of nozzles we may make nozzle member 22 in two parts. One part which includes the stop 35 and which is threadedly connected to body portion 33 may have a threaded socket in its outer end which serves detachably to receive a threaded nozzle tip which has the small bore outlet 30 therein.

I claim:

1. Apparatus for applying adhesive to successive articles such as paper sheets wherein said sheets are successively moved past a gluing station, comprising: a glue delivering nozzle at said station; a deformable bag containing a supply of glue; conduit means connecting the interior of said bag to said nozzle and including a solenoid operated valve, said conduit extending through said solenoid and defining a valve seat; said solenoid operated valve including a valve element engageable with said seat to close said conduit and movable away from said seat in the direction of glue flow through said conduit; means for applying air pressure to substantially the entire exterior surface of said bag; and trigger means operable by an article at said station for operating said solenoid to open and close said valve.

2. Apparatus as defined in claim 1 wherein said trigger means comprise photoelectric devices responsive to said articles at said station.

3. Apparatus as defined in claim 1 wherein said trigger means comprises two photoelectric devices responsive to said articles and arranged to, respectively, cause said solenoid valve to open and close.

4. Apparatus as defined in claim 3 wherein said photoelectric devices are spaced apart in the direction of article travel; said nozzle being positioned between said devices; and means mounting said nozzle and devices for relative adjustment in said direction whereby to vary the length of glue line applied to each article.

References Cited by the Examiner UNITED STATES PATENTS 1,911,094 5/1933 Skoglund 222389 2,606,698 8/1952 Todd et al 222400.7 2,925,102 2/ 1960 Cummings, et al. 222504 X 2,979,231 4/1961 Witherspoon 222504 X 3,065,775 11/1962 Keves 222318 X LOUIS J. DBMBO, Primary Examiner.

HADD S. LANE, Examiner, 

1. APPARATUS FOR APPLYING ADHESIVE TO SUCCESSIVE ARTICLES SUCH AS PAPER SHEETS WHEREIN SAID SHEETS ARE SUCCESSIVLY MOVED PAST A GLUING STATION, COMPRISING: A GLUE DELIVERING NOZZLE AT SAID STATION; A DEFORMABLE BAG CONTAINING A SUPPLY OF GLUE; CONDUIT MEANS CONNECTING THE INTERIOR OF SAID BAG TO SAID NOZZLE AND INCLUDING A SOLENOID OPERATED VALVE, SAID CONDUIT EXTENDING THROUGH SAID SOLENOID AND DEFINING A VALVE SEAT; SAID SOLENOID OPERATED VALVE INCLUDING A VALVE ELEMENT ENGAGEABLE WITH SAID SEAT TO CLOSE SAID CONDUIT AND MOVABLE AWAY FROM SAID SEAT IN THE DIRECTION OF GLUE FLOW THROUGH SAID CONDUIT; MEANS FOR APPLYING AIR PRESSURE TO SUBSTANTIALLY THE ENTIRE EXTERIOR SURFACE 